#include<iostream>
using namespace std;

/* example 1 --------
#ifdef tag
    code 1
#else
    code 2
#endif
// ------------------

// example 2 --------
#ifdef tag
    code 1
#else
    code 2
#endif
// ------------------*/

#define _DEBUG_
int main(void)
{
    int x = 10;

#ifdef _DEBUG_
    cout<<"File:"<<__FILE__<<",Line:"<<__LINE__<<",x:"<<x<<endl;
#else
    printf("x = %d\n" x);
    cout<<x<<endl;
#endif

    return 0;
}